Screen printing which forms a print film comprising ink, paste or the like on the surface of a material to be printed using a printing plate for screen printing (hereinafter sometimes referred to as merely “screen printing plate” or “printing plate”) can form fine patterns and has high mass-productivity, and hence is utilized in a wide variety of industrial fields. In general, screen printing is a method which uses a screen mask constructed by stretching onto a printing plate frame a mesh having openings closed with a resin (such as photosensitive emulsion film), an ink material is then placed on the upper face of the screen mask and a squeegee is slid, thereby squeezing out the ink material to the under side of the screen mask (substrate side) through the given openings formed in the screen mask to perform the printing.
According to this screen printing method, since the screen mask is flexible and besides the printing pressure is low, it is possible to carry out the printing on various printing materials, such as papers, fabrics, plastics, glasses, metals, and ceramics. Furthermore, since patterns formed by ink materials can be made thick, the screen printing can also be applied to production of electronic parts such as thick film IC (hybrid IC), printed-wiring boards, resistors and capacitors. The screen mask is produced by patterning a photosensitive emulsion film coated on a mesh by photolithographic technology. It is also produced by forming mesh patterns by selectively etching a metallic film by photolithographic technology.
General screen printing plates used for screen printing have a film-like screen having a support member comprising a gauze and a mask material having openings of a given shape and placed on the support member and a printing plate frame on which the screen is stretched. In printing, first the screen of the screen printing plate is placed on the surface (the surface to be subjected to printing) of a suitable printing material, and ink or paste is applied to the screen. Then, a squeegee or the like is slid across the screen to squeeze out the paste or the like from the openings, whereby print patterns corresponding to the shape of openings or the arranged patterns when a plurality of openings are formed on the surface of the printing material.
For example, in the field of electronic part production, the above screen printing method may be employed from the points of both precision and mass-productivity. In this field, the demand for forming finer print patterns with high precision has steadily increased due to the recent development of technology to miniaturize the size of the parts.
However, a printing plate frame may have some distortion, and hence it is difficult to make a completely flat screen stretched on the printing plate frame. Moreover, since the distortion of the printing plate frame differs depending on the printing plate frame, the arranged patterns of the openings on the screen stretched on the printing plate frame also delicately differ depending on the respective screen printing plates. Therefore, there is a problem that when the screen printing is carried out using a plurality of screen printing plates in the arranged patterns of the openings, the print patterns on the respective resulting screen prints may delicately differ from each other.
Recently, substrates which are to be printed tend to become larger, and hence the screen (screen printing plate) used for printing on large-sized substrates similarly tends to be large-sized. Therefore, due to the increase of the size of the substrates or the screen printing plate, the difference in print patterns of the respective resulting screen prints has further become evident.
The degree of difference in opening patterns of respective screen printing plates is not particularly significant as long as it is within a specific tolerance permissible for the respective prints obtained by the printing. However, with recent progress in miniaturation technology, the screen printing precision must further be improved. Particularly, in the case of making laminated electronic parts by laminating screen prints, a slight deviation of printing position between the screen prints will result in more conspicuous deviation caused by lamination of the screen prints. Therefore, in order to make laminated electronic parts with higher screen print performance, it is important that the degree of deviation in the printing position of the screen prints remains within a permissible specific tolerance range.
As relevant prior art, there are disclosed a printing plate for screen printing in which the crossing portion of wire (gauze) constituting the support member of screen is fastened (Patent Document 1), a printing plate for screen printing in which linear expansion coefficient of printing plate frame is specified (Patent Document 2), a method of screen printing in the state of a given side of a printing plate frame being curved in a convex form (Patent Document 3), and a printing plate for screen printing provided with a printing plate frame deformable in both the outer and inner directions, as well as a method for producing prints using the same (Patent Document 4). However, even these printing plates for screen printing or printing methods using them cannot sufficiently meet the high printing precision demands that need to be assured and the degree of deviation in the printing position that needs to be maintained within a permissible range so that further printing improvement is achieved.
Patent Document 1: JP-A-9-136394
Patent Document 2: JP-A-11-34288
Patent Document 3: JP-A-2000-318120
Patent Document 4: JP-A-2006-62241